This invention relates to an apparatus for cleaning paint applicator heads, e.g. paint atomizer heads used for applying paint to automotive vehicles.
Paint atomizer heads are used during the automotive vehicle manufacturing process to coat the vehicle exterior surfaces with various different colored paint. In conventional automotive vehicle manufacture the vehicle bodies are painted in a tunnel-type paint booth. Typically the skeleton bodies are placed on a conveyor that moves slowly through different chambers in an elongated tunnel (or booth). As each vehicle body moves slowly along the tunnel different painting operations and drying operations are preformed on different surfaces of the vehicle body.
Various different paint colors are applied to the different vehicle bodies, depending on production requirements. Periodically, it is necessary to change the paint coloration supplied to the paint applicator mechanisms, e.g. when one vehicle is to have a blue coloration and the next vehicle body is to have a red coloration.
When it is necessary to change the paint coloration supplied to the paint applicator mechanisms, a paint solvent is passed through the paint supply passages, paint applicator mechanisms, and paint return passages. The solvent initially acts as a pump to move most of the paint out of the passages, and later as a cleaner to dissolve and remove residual paint from the passage walls. The process of removing paint from the various passages is sometimes referred to as the purge cycle. Typically the purge cycle takes about fifteen or twenty seconds while the vehicle bodies continue moving along the conveyor. The vehicle bodies continually move through the paint booth during the purge cycle and during the time required to load the new paint coloration into the applicator mechanisms.
One type of paint applicator mechanism commonly used is a rotary paint atomizer head. Typically, the paint atomizer head is connected to a rotary hollow shaft that supplies paint to a central chamber in the atomizer head. Paint flows from the central chamber onto a dish-like surface of the head, where centrifugal force causes the paint to be thrown off the outer peripheral edge of the head toward the vehicle surface.
During the aforementioned purge cycle, paint solvent is pumped into the central chamber of the paint atomizer head, so that paint on the head surfaces is assimilated into the solvent, whereby the head surfaces are cleaned for receiving new paint colorant.
The purge cycle is of relatively short duration so that in some cases residual traces of paint may remain on certain surfaces of the atomizer head. Over time these paint accumulations can adversely affect the flow of paint through the atomizer head, or otherwise degrade the painted vehicle surface to a point where excessive manual sanding operations are required on the vehicle.
It is a practice to periodically remove the atomizer heads from the paint supply apparatus for hand cleaning or replacement with new atomizer heads. Hand cleaning is time-consuming and hence costly. The present invention relates to a cleaning system for paint applicator heads (paint atomizer heads) that is efficient and at the same time relatively automatic, whereby a given cleaning operation can be performed with minimal human effort. The principal aim of the invention is to reduce the cost of the paint application head cleaning operation. An apparatus embodying the invention can include a treatment tank containing a piping system designed to supply paint solvent to several discharge fittings. Each fitting is connectable to an individual paint applicator head, whereby solvent is caused to flow from the piping system through the applicator heads into the tank interior space.
The solvent, with entrained paint particles, collects in the bottom of the treatment tank, from where it is passed through an external filter for removal of the paint particulates. A motor-operated pump returns the solvent to the aforementioned piping system for recirculation through the applicator heads.
The cleaning apparatus enables the solvent to be recirculated and reused on a continuing basis, without any requirement for human control or human attention. A cleaning operation can be performed automatically for a given time period, e.g. one hour, after which the applicator heads can be removed from the treatment tank in cleaned conditions.
A principal advantage of the invention is that the cleaning operations can be carried forward for an extended period of time, without human attention or control, so that the cleaning operation is relatively inexpensive. The apparatus can include multiple fittings within the treatment tank, whereby several paint applicator heads can be cleaned at the same time, thereby reducing the cost for cleaning each paint applicator head. Various types of paint applicator heads and paint nozzles can be treated (cleaned) in a given apparatus. The apparatus has general application for a range of cleaning functions.
Specific features and advantages of the invention will be apparent from the attached drawings and description of an apparatus embodying the invention.